Spark plug



Patented Apr. 21, 1936 UNITED STATES PATENT OFFICE SPARK PLUG Application November 30, 1934, Serial No. 755,385

2 Claims.

My invention relates to spark plugs of the kind especially designed for use in high compression cylinders.

One of my objects is the provision of a spark plug having a spark gap within the socket of the shell and at the point of greatest efliciency within the socket.

Another of my objects is the provision of a spark plug having a spark gap positioned appreciably within the socket and so arranged that the electrodes may be readily adjusted for increasing or decreasing the space between the electrodes.

Another of my objects is the provision of a ground electrode which is declined from a special combustion ring fitted high in the base.

A very important object in my invention is the provision of a ground electrode which is anchored to the special combustion ring within the spark plug by the distortion of the metal of the ring and of the electrode.

Having in view these objects and others which will be pointed out in the following description, I now refer to the drawing in which Figure 1 is a view partly in elevation of the entire spark plug .and partly in section of the shell, the washers, gasket, and combustion ring, the figure being drawn to an enlarged scale.

Figure 2 is a view showing the combustion ring with the ground electrode attached in section, showing a modification of my invention, the view being drawn to show the position of the electrodes in case of hot motors.

Figure 3 is a view showing the combustion ring with the ground electrode attached in section, showing a modification of my invention, the view being drawn to show the position of the electrodes in case of medium cool motors.

Figure 4 is a View showing the combustion ring with the ground electrode attached in section showing a modification of my invention, the view being drawn to show the position of the electrodes in case of a cold motor.

Figure 5 is a view showing the combustion ring with the ground electrode attached in elevation to more clearly disclose the anchor of the ground electrode.

The spark plug as shown includes a shell I0, 2. core II, of stone or porcelain or other dielectric, a bushing I2, and a gasket I3, the core II having a rib I I.

The central electrode I5 passes through the core II and terminates at its upper extremity in a screw threaded portion for receiving the nut I9. As thus far described the structure is well known, being common to spark plugs of many types. As is usual in spark plugs, the gasket is made of a relatively soft material having high thermo-conductivity. The gasket should be sufficiently soft to yield slightly under compression in order to provide an effective seal. Since one of its chief functions is to conduct the excess heat to the shell I and to thus dissipate the heat, it must be made of an effective heat conducting material.

The core II is provided with lower and upper annular shoulders for seating the gaskets I3 and M in a manner such that both gaskets will be compressed when the bushing I2 is forced down into the shell Ill. It should also be noted that the parts are so proportioned that an elongated annular air space will be formed between the shell Ill and the core II as shown in Figure 1. This annularair space functions to assist in the dissipation of the excess heat through the shell I0.

My spark plug includes a detachable ring I6 for supporting the ground electrode I'I. This ring is fiared outwardly to provide a fiange which rests on an inner shoulder of the shell I0 as shown in Figure 1. The ring is of a size such that it nowhere contactswith the core I I which it surrounds. This is due not only to its larger diameter than that of the core but also to the inner bevel in the upper portion of the ring I6 as clearly shown in Figure 5. This construction has for its purpose the provision of an unob structed passageway for the hot gases of combustion, the passageway extending from the gasket I3 to the-mouth of the spark plug. This passageway is of importance in dissipating the excess heat and in thus lowering the temperature of the spark plug, this being of prime importance in spark plugs which are to be used in high compression motors.

In the present instance instead of the electrode I extending to within close proximity of the mouth of the shell III, the electrode is shortened to bring the extremity into a position of maximum efliciency of the spark gap in high combustion cylinders.

The ground electrode I! then approaches the electrode I5 from the combustion ring I6 near the center of the shell I0, passing first in a declined position towards the center of the spark plug and away from the combustion ring, the direction then being changed abruptly so as to approach the electrode I5 at an angle more nearly approaching right angles.

In anchoring electrode IT in the combustion ring I6, I first drill an aperture through the center of the base of the combustion ring. This aperture is of a diameter to snugly receive the electrode I'I.

When the electrode has been inserted in the aperture thus formed, a center punch is applied at the point I8 and is given a sharp blow which distorts the metal of the combustion ring I 6 and of the electrode H, which will hold the electrode in place regardless of the heat fluctuation in the spark plug. Neither the concussions of the explosion nor the ordinary mechanical blow can loosen the electrode which is thus anchored in the shell.

The construction not only provides afirrn and secure anchor for the ground electrode but leaves the two electrodes in such relative positions that they may be easily adjusted for increasing or decreasing the length of the spark. If greater separation is required, a screw driver inserted between the two points may be used to spread the points.

If it is desired to bring the two points closer together all that is required is to introduce a screw driver between the electrode I1 and the shell Wall and to thus force the electrode I! toward the electrode I5.

The ring I6 also has a very definite function in the adjustment of the spark gap. In a very hot motor the position of the gap should be in close proximity to the mouth of the spark plug. In a cold motor the gap should be in close proximity to the tip of the core II. In case the motor pumps oil and fouls the spark plug, the firing should take place as far as possible from the mouth of the spark plug so that the oil and carbon will be burned out as fast as it accumulates. The ring I6 makes such adjustment an easy matter. The spark plug is taken apart and the electrode I7 is out to the desired length after which the spark plug is again assembled. The ring I6 also facilitates and simplifies the stocking of the spark plugs by dealers. The ring I6 with its ground terminal I? may be carried in stock in various lengths of the terminals I'I so that the assembly may be made to suit the particular conditions for which the spark plug is to be used.

The ring I6 comprises a substantially cylindrical body I9 which has a diameter smaller than the interior diameter of the shell ID below the shoulder 2I formed on the interior thereof so that the body I9 will not stick to the inside of the shell I after the spark plug has been in use for a period of time. As shown in Fig. 1 there is a substantial space between the inside of the shell I0 and the exterior of the body I9 below the shoulder 2|. The body I9 at its upper end is provided with a tapering flange 23 of substantially inverted frustro-conical configuration which is adapted to rest upon the shoulder 2I which is of similar shape. By providing the flange 20 and the shoulder 2| of tapering construction, when the bushing I2 is tightened to force the core II downwardly, the ring I6 will more readily seat on the shoulder 2| so that no gases will leak past the ring I6. Through the use of a construction of this kind the spark plug can be marketed with a set of rings each having different length electrodes I'I, so that the purchaser can determine exactly which type of electrode H to use, and if it is found desirable to change electrodes after the plug has been in use for a period of time, a different type may be substituted, so that a single plug of this character will serve a three-fold purpose as shown in Figs. 2, 3 and 4.

Having thus described my invention in such full, clear, and exact terms that its construction and operation will be readily understood by others skilled in the art to which it pertains, what I claim as new and desire to secure by Letters Patent of the United States is:

l. A spark plug comprising a member having a bore therethrough and a shoulder intermediate the ends of the bore, an insulated core within the bore and having its lower end disposed inwardly of the lower end of the member, a rib on the core, a bushing threaded into the member to releasably hold the core in the member, an electrode axially of the core and terminating adjacent the lower end of the member, a ring having a cylindrical peripheral surface loosely disposed in the bore and having a diameter less than the inner diameter of the bore below the shoulder whereby to provide a space between the ring and the interior of the member, a fiange carried by the ring engaging the shoulder, an electrode carried by the ring and extending downwardly and in the direction of the first electrode, and a gasket interposed between the flange and the rib.

2. A spark plug comprising a member having a bore therethrough and a tapering shoulder intermediate the ends of the bore, an insulated core within the bore and having its lower end disposed inwardly of the lower end of the member, a rib on the core, a bushing threaded into the member to releasably hold the core in the member, an electrode axially of the core and terminating adjacent the lower end of the member, a ring having a cylindrical peripheral surface loosely disposed in the bore and having a diameter less than the inner diameter of the bore below the shoulder whereby to provide a space between the ring and the interior of the member, an upwardly flaring flange carried by the ring and engaging the shoulder to support the ring therefrom, an electrode carried by the ring and extending downwardly and in the direction of the first electrode, and a gasket interposed between the fiange and the rib.

ELMER P. HANSEN. 

